Transparent and semitransparent substrates are presently used in a vast number of applications. For example, most consumer electronics devices such as cellular phones, “smart” phones, tablet computers and the like include glass, sapphire, and/or glass-like substrates to protect display devices, cameras, and the like. Further, electronic devices incorporating touch-screen technology displays are becoming commonplace. In addition, transparent and semitransparent substrates such as various glasses are frequently used in microelectronics packaging, solar cell manufacturing, aerospace applications, medical devices, manufacturing systems, and the like. As a result, glass substrates are presently manufactured in a wide variety of sizes and shapes with any variety of geometric features formed therein.
Currently, there are a number of processes used to manufacture glass substrates. For example, mechanical drilling, cutting, sand-blasting, and surface polishing are all processes used to some degree for fabricating various features in a glass substrate. While these mechanical processes have proven somewhat useful in the past, a number of shortcomings have been identified. For example, consumable materials are used in mechanical processing. As such, the cost of processing is somewhat variable depending on the cost of consumable materials. In addition, consumption and disposal of such consumables may also be environmentally undesirable or problematic. Further, mechanical processing may be a labor intensive, time consuming process that may not provide the requisite accuracy and precision for many applications.
Increasingly, however, lasers are being used for processing glass or similar transparent/semitransparent substrates. Unlike mechanical processes, the laser-based processing techniques do not require the use of consumable materials. In addition, high-quality laser processes require less post-processing procedures (i.e. polishing, etc.) than mechanical processing. As such, laser-based processing offers a throughput and accuracy advantage over comparable mechanical processing.
Presently, CO2 laser processing is a well-known laser based glass-cutting process, most typically used for cutting glass in straight-lines and curves with very large radii of curvatures (curves with a radius of curvature greater then several centimeters). This process typically uses a CO2 laser to locally heat the glass and a trailing cooling gas jet to cool the glass, resulting in a fracture propagating in the approximate direction determined by relative motion between the glass substrate and the CO2 laser beam/gas jet. Typically, CO2 laser processing is used for crude but fast straight-line cutting of relatively large glass sheets. While CO2 laser processing has proven to be somewhat useful, a number of shortcomings have been identified. For example, cutting intricate shapes, small holes (less than about 200 mm), and curved lines (curves with a radius of curvature of less than about 200 mm) with CO2 laser processes has proven to be problematic.
As a result, alternate laser-based glass cutting systems have been developed. For example, pulsed laser system have been used to create so-called “stealth dicing” cutting processes. These pulsed laser-based cutting processes use pulsed laser sources to create sub-surface modification features (cracks, melt zone, refractive index change) that are used to guide a cleaving fracture along an intended linear path. The very common application of this technology is for dicing of micro-electronic and micro-optical devices built on, for example, crystalline silicon (integrated circuits) and sapphire (light-emitting diodes) wafer substrates. Similar laser-based cutting processes have been developed for cutting high stress, thermally and/or chemically strengthened glass (for example, “Gorilla Glass” manufactured by Corning, Inc., “Dragontrail” manufactured by Asahi Glass, “Xensation” manufactured by Schott, etc.). While the various pulsed laser-based cutting processes have proven somewhat successful in the past a number of shortcomings have been identified. For example, these prior art laser-based cutting processes and systems have been largely unable to efficiently and effectively cut or separate glass along curved paths with small radii of curvature (e.g. radius of curvature of less than about 100 mm).
In light of the foregoing, there is an ongoing need for a method and apparatus for effectively and efficiently cutting transparent and semitransparent substrates in any variety of desired shapes.